Foreign Keys Relation - Unique tuple

Question

Let's say I have a 3rd table that stores data from two other tables...

fk_first_table | fk_second_table
1 | 1
1 | 2
1 | 3
1 | 4
2 | 1

...

How can I assure that both keys never repeat... Forming a unique tuple... Kind of unique together like a table of truth.

Answer 1

CREATE UNIQUE INDEX my_index ON tbl_name (fk1, fk2)

Answer 2

您需要创建一个唯一索引：

CREATE UNIQUE INDEX indexName ON thirdtable (fk_first_table, fk_second_table)